Watershed Management: Watershed Planning
Red tide is a type of harmful algae bloom (HAB) caused by an abnormal increase or “bloom” in the concentration of certain microscopic algae in the water column. Red tide events have been noted in Florida since the 1800’s and most certainly occurred prior to European settlement. The most common alga that causes red tide in Florida is the dinoflagellate Karenia Brevis. In high enough concentrations the alga turns the water column a distinct red color. The toxin produced by the alga can affect the central nervous system of fish and other marine life. No human deaths have been attributed to red tide, however respiratory and skin irritations have been reported. Shellfish should not be consumed during a bloom, however shrimp, crabs and fish can be consumed during a red tide.
There are numerous poorly understood factors that are associated with red tide which make it hard to determine when and with what severity a bloom will occur. Experts believe that heat combined with rainfall is a possible causes of red tide. Some have blamed red tide on runoff of nutrients or pesticides but there is no scientific evidence to definitively conclude these are contributing factors.